Alkylation of paraffin hydrocarbons



memes July 2 1943 nF- TAT S" PATENT OFFICE ALKYLATION OF PARAFFIN HYDROCARBONS Aristid V. Grosse Bronxville. N. Y., and Carl n. Linn, Chicago, 111., assignors to Universal Oil Products Company, Chicago, 111., a corporation 01' Delaware Application September 9, 19"10, SerialNo. 355,936

10 Claims. (Cl. Mil- 683.4) j 4 This application is a continuation-in-part of our co-pending application Serial No. 248,777,

filed December 31, 1938, now Patent No. 2,267,730,

December 30, 1941.

This invention relates to the interaction 01 isomeric or branched chain paraflin hydrocarbons and mono-olefinic hydrocarbons in the presence of catalysts.

Phosphoric acid his "a limited application at the reactions are not accelerated to'a practical degree unless undesirably high temperatures are employed. Aluminum chloride and similar multivalent metal salts present the usual'disadvan- .tages inherent in'the use oi. solid granular catalysts in thatthe efliciency ot-the reaction is to It is more specifically concerned with a simple .and easily regulated .process involving the use of a liquid catalyst which is substantially unaltered in the course of the reactions and which catalyzes the desired reactions with a maximum of efllciencyt Processes for the formation of higher molecular weight branched chain hydrocarbons from essome extent contingent 0n the fineness oi subdivisionvof the catalyst. and that recovery oi. the active salts from their sludges is diflicult and expensive. The use 01. boron fluoride is-not practical on account 01' the cost or this compound.

4 I In onespeciflc embodiment the present invention comprises a process for continuously alkylatsentially straight chain compounds or less highly branched compounds are of present importance from the standpoint of the motor fuel industry which demands increasing quantities of iso-paraffins .within the boiling range of gasoline and particularly iso-octanes, such as, for example, the

2,2,4-tri-methyl pentane which forms the standard of reference in rating the anti-knock value or gasolines. Considerable quantities of butanes and butenes are available as by-products from the cracking of petroleum fractions to produce relatively high primary yields of gasoline and by proper segregation of butanes and butenes by solvent extraction and fractionation methods, I particular cuts are available for recombination to produce material yields of the desired iso-octanes.- Efforts to alkylate normal butane with butenes ing iso-paraflin hydrocarbons with mono-oleflnic hydrocarbons in the presence of liquid hydrogen fluoride, the process being conducted in a reactor coil with an excess of iso-paraflln flowing therethrough while olefins and hydrogen fluoride are introduced at intermediate points along the line oi flow.

We have determined that whereas previous work in alkylating various classes or hydrocarbons with oleflns has indicated that the reactions could be brought about in the presence of boron fluoride and minor amounts of h drogen fluoride, the reactions are better brought about when using merely liquid anhydrous hydrogen fluoride. This catalyst is a liquid boiling atabout 20 C. so that it can be used in apparatus which'is'cooled to maintain temperatures below this point or can be used at higher temperatures'if sufllcient presin the presence of catalysts have thus far failed the present invention. Sulfuric acid, for example, can not be used to effect alkylation with ethylene and gives very'poor yields when propylene is used. Furthermore, this acid has a tendency to oxidize hydrocarbons with the formation of sulfur dioxide so that the catalyst is gradually lost by. reduction and the products of the reactions are contaminated with sulfur compounds .and oxidation pro ducts.

sures are maintained upon the apparatus. By

maintaining an excess of iso-paraflin .at all times, I

polymerization reactions and the formation 01 alkyl fluorides are minimized so that the products consist principally of alkylated derivatives of the original iso-paraflins. The catalyst is not changed by oxidation or reduction and it lost mechanically it can be readily recovered and reused whileany alkyl fluorides formed are read ily decomposable.

We have now further found that still better" results in the 'alkylation of iso-parafllns with olefins in the presence of hydrogen fluoride are brought about when the catalyst and the oleflns are injected at successive points along the line of flow of the iso-butane through a continuous reaction coil. By the step-wise and successive injection of the olefins, -the iso-butane is maintained in relatively large excess so that alkylation rather than polymerization reactions are fostered and hydrogen fluoride is added in a similar manner to compensate for any losses which of interconnected units suitable for continuous alkylation operations. It is understood that minor features of apparatus construction may be modified without departing essentially from the generally broad scope of the invention.

Referring to the drawing, liquid iso-paraflin hydrocarbons such as, for example, iso-butane may be introduced through line I containing valve 2 to line 3 containing valve 4 leading to pump 5 while an initial amount of liquid hydrogen fluoride is introduced to line 3 by way of line 6 containing valve I. Pump 5 discharges through line 8 containing valve 8', line 8 receiving from line 23 separated and recirculated liquid hydrogen fluoride and if desired, a portion of the alkylate or recycled isobutane for further alkylation. The sources of these recycled materials will be described at a later point. In accordance with the present invention the mixture of olefins, iso-paraflin, and hydrogen fluoride is passed through a continuous coil cooler l4 in which an optimum reaction temperature is maintained depending upon the particular iso-paraffins and oleflns undergoing reaction and the type of alkylation desired. The discharge from-pump 5 enter the coil through valve 8' while an olefln or a mixture of oleflns is introduced by pumping means not shown into a header 8" havin branch line 9 containing valve l0, and similar branch lines 8' containing valve l0, 9" containing valve l0, and 9" containing valve l0'. In a similar manner, necessary amounts of hydrogen fluoride catalyst may be introduced from header-l i into branch lines l2 containing valve l3, l2 containing Valve l3, l2" containing valv l3", and i2 containing valve l3'. The reaction products follow line containing valve ii to a receiver I! in which a separation or hydrogen fluoride and hydrocarbons is eflected. The liquid hydrogen fluoride is withdrawn from the receiver through a line i 8 containing valve l9 and returned by pump which discharges through line 2| containing valve 22 into line 23 leading to the suction side of pump 5 so that the hydrogen fluoride catalyst is completely recycled.

The hydrocarbon layer in the upper portion of receiver I1 passes through line 24 and valve 25 and enters ,fractionator 26 containing a reboiler 21, unconverted low boiling hydrocarbons being removed as overhead while higher boiling alkylated products of the reaction are withdrawn through line 28 containing valve 29 from the bottom of the column.

The overhead products pass through line 30 containing valve 3| through condenser 32 and thence through rundown line 33 containing a valve 34 to receiver 35 which has a conventional gas release line 36 containing valve 31 and a liquid draw line 38 containing valve 39 leading to a pump 40 which discharges through line 4| containing valve 42 to storage, but also if desired through line 43 containing valv 44 and leading to line 23 to permit the further alkylation of the paraffins. When individual iso-paraffins such as i-butane are being alkylated this may be recycled for further alkylation from gas vent line 36- containing valve 31 although specific means for accomplishing this recycling are not shown in the drawing. Such means may include compressors and coolers for liquefying the hydrocarbon and returning itto line 43 or directly to line 3 while the alkylated product is completely removed by way 01' line 4| and valve 42, valve 44 being closed. I

The exact temperatures and pressures which should be employed when alkylating various isoparaflins with various olefln will depend upon the activity and physical characteristics of the hydrocarbons involved so that best results will be obtained when conditions are flrst determined in small scale apparatus. Temperatures which may be employed with different combinations of iso-paraflins and oleflns to effect varying degrees of alkylation may vary from about 30 to +100 C. although as a rule temperatures will be comprisedwithin a much narrower range of the order of from 0 to 50 C. In regard to pressures the only requirement is that sufficient pressure should be used to p event material vaporization or the reacting hydrocarbons or the hydrogen fluoride catalyst.

For the recovery for reuse of hydrogen fluoride which combines to some extent with oleflns to form alkyl fluorides in the course or the alkylating reactions, these fluorides may be passed over granular fluorides such as calcium fluoride or aluminum fluorides which decompose them into hydrogen fluoride and the corresponding oleflns. The mixture of olefin and hydrogen fluoride is then passed over solid granular sodium or potassium fluoride which forms addition compounds of the type NaF.HF. The oleflns liberated may be recycled for further use and the hydrogen fluoride recovered from the double salt by heating.

The following experimental data is given by way of example toindicate the results obtainable when utilizing the present process for alkylating iso-butane with butenes to form isooctanes. This example has been chosen because 01' its commercial importance, but it is not to be inferred that the scope of the invention is limited in exact correspondence with the data presented.

Iso butane is alkylated with normal butene, using 100% hydrogen fluoride as catalyst, a temperature of 20 C. and a process flow similar to that described in the preceding specification. A mixture of approximately 100 parts of iso-butane and 10 parts of hydrogen fluoride is pumped through a coil while the' normal butene and hydrogen fluoride are introduced along the line of flow. The oleflns are introduced at a rate to obtain a 100:1 ratio 01' iso-butane to normal butene and the hydrogen fluoride is introduced so as to maintain an effective concentration of hydrogen fluoride equal to approximately 0.1 volume oi the iso-butane present. A 60% yield of octanes consisting largely of 2,2,4-trimethyl pentane is obtained in a single pass while the yield is increased to of the theoretical by recycling or the unalkylated iso-butane. The alkylate contains less than 0.2% of fluorine.

We claim as our invention:

1. A process for alkylating iso-paramn hydrocarbons with olefln hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said isoparaffln hydrocarbons and hydrogen fluoride through a reaction zone of relatively small cross section in proportion to its length while introduclng successive portions 01' said olefin hydrocarbons along the line of flow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

2. A process for alkylating iso-parafiin hydrocarbons with olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said isoparafiin hydrocarbons and hydrogen fluoride at a temperature of from about -30 to about +l C. through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions of said olefin hydrocarbons along the line of flow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

3. A process for alkylating iso-parafiln hydrocarbons with olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said isoparafiin hydrocarbons and hydrogen fluoride at a temperature or from about -30,to about +100 C. and under a pressure adequate! to prevent substantial vaporization of the reactants, through a reaction zone of relatively small cross section in proportion to'its length while introducing successive portions of said olefin hydrocarbons along the line of flow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

4. A process for alkylating iso-butane with normally gaseous olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said isobutane and hydrogen fluoride through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions of said olefin hydrocarbons along the line of flow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

5. A process for alkylating iso-butane with normally gaseous olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture or said iso-butane and hydrogen fluoride at a temperature of from about 30 to about +100 C. through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions oi! said olefin hydro-' carbons along the line of flow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

6. A process for alkylating iso-butane with normally gaseous olefin hydrocarbons in the presence 01 hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said iso-butane and hydrogen fluoride at a temperature of from about -30 to about C. and under a pressure adequate to prevent substantial vaporization of the reactants, through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions or said olefin hydrocarbons along the line of fiow in said reaction zone and simultaneously introducing hydrogen fluoride along the line of flow.

'7. A process for alkylating iso-paraflin hydrocarbons with olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said iso-paraflin hydrocarbons and hydrogen fluoride at a temperature of from about 30 to about +100 C. and under a pressure adequate to prevent substantial vaporization of the reactants, through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions of said olefins along the line of flow in said reaction zone, simultaneously introducing hydrogen fluoride along the line of flow, and maintaining a molal excess of said iso-parafiin hydrocarbons in respect to said olefin hydrocarbons.

8. A process for alkylating iso-butane with normally gaseous olefin hydrocarbons in the presence of hydrogen fluoride as a catalyst which comprises continuously passing a mixture of said iso-butane and hydrogen fluoride at a temperature or from about 30 to about +100 C. and under apressure adequate to prevent substantial vaporization of the reactants, through a reaction zone of relatively small cross section in proportion to its length while introducing successive portions oi! said olefin hydrocarbons along the line of flow in said reaction zone, simultaneously introducing hydrogen fluoride along the line of flow, and maintaining a molal excess of said iso-butane in respect to said olefin hydrocarbons.

9. In the catalytic alkylation of iso-paraflins with olefins in the presence or hydrogen fluoride as the alkylating catalyst, the method which comprises passing a stream 01 iso-paraflin hydrocarbons through a reaction zone maintained under alkylating conditions. successively adding increments of olefin hydrocarbons and hydrogen fluoride to said stream by introducing the same at spaced points along the line of flow through-the reaction zone, and reacting a substantial portion or the iso-paraflin with olefin hydrocarbons during the passage thereof through the reaction zone.

10. The process asdefined in claim 9 further characterized in that the olefin hydrocarbons and the hydrogen fluoride are separately introduced at spaced points along the line of flow 'oi the isoparaflin stream through the reaction zone.

ARISTID v., bnossn. osm- B. mm. 

